I feel it is really the first controller to cover all the features one could want. 2 USB ports, 4 channel analog mixer with hardware effects and oscillator. Full size CDJ jog wheels, full sized touchpads. It's large and with the road case is pretty heavy.

You can get a good Windows machine for about the same cost as the controller. I'd go with a Dell.
Apple is a great way to go if you can afford it, would be worth looking at a refurbished model, macmall or craigslist for a used one. Look for an 'i' like an i5 or i7 series processor.
[serato.com]
reads that it is not supported officially, but that many users are running Win8 without issue.
I have found that the big problem with Windows is when you attempt to attach your existing database that was build on a Mac to a Windows machine. This introduces a lot of problems, but if you are starting with a clean database, you should be OK.

Not sure, I've only gone from Mac to a Windows backup machine in a pinch. The crates loaded but would crash if you tried to actually play a track. I was able to browse the file system and load tracks that way but I don't organize in the file system so it was a difficult gig.
I can't really stress enough how stable it is on a mac. If stability is what you need, there isn't really a better choice.